Thursday, December 21, 2017

Sandblasting on Denim | Health Problems in Sandblasting

What is Sandblasting? Sandblasting is a mechanical process in which localised abrasion or colour change on the denim garment
is created. The process involves blasting an abrasive material in
granular, powdered form at a very high speed and pressure through a
nozzle, on certain areas of the garment such as knees and elbows as
shown in Figure. The treated surface shows distressed/abraded/used look.

Figure: Sandblasting on denim

The common blasting materials used are sand and metal granules. During sandblasting process, denim
garments are first subjected to stone washing to the desired degree of
washing and are then sand blasted. A solution of sodium hypochlorite or
potassium permanganate is often sprayed on the desired area of the
garment in order to obtain the same look. The garment is then
neutralised, rinsed, softened and dried. Sand blasting is a water free
process and, therefore, no drying is required.

An air compressor is started and pressure is maintained at 3–4 kg/cm2.

The air compressor then stores air in the machine’s cylinder.

Aluminium sand or silicon sand [Al2(SiO4)3] is then put in the chamber of the blasting machine.

Sand and compressed air are then sprayed over the garments at specific points at a 10–200 degrees angle by a hand spray pipe.

Sand passes into the machine by a regulating system.

The
machine is composed of a blasting regulator and a hand regulator to
control the amount of sand and compressed air, respectively.

The
angle of sand blowing is important. The higher the blowing angle, the
higher the fading effect is and higher the risk is of fabric damage.

Fading is done on premarked areas.

Sandblasting is a hazardous technique; therefore the area should be isolated from other work areas.

Handling
the sandblasting gun is risky; therefore operators should use safety
equipment such as hand gloves, masks and gowns. Production/hours/guns
vary from 25 to 45 garments, depending on the degree of fading and the
extent of fading to be attained.

The
faded garments are cleaned by shaking them manually. After sandblasting,
garments are washed. The technique used may be normal washing or bleach
or bio-stone washing.

Health problems in sandblasting: Sandblasting
removes the dark indigo from a denim garment giving it a popular
pre-worn look. This process involves smoothing, shaping and cleaning a
hard surface by forcing abrasive particles across that surface at high
speeds using special types of sands. These are sprayed onto the selected
parts of the denim garments at high pressure through air compressors to
remove colour from those areas to create the desired design.

Sand
blasting can be done manually or mechanically. The mechanical process
encloses the sand and dust particles in blasting cabinets and is–if used
correctly–therefore less hazardous for the operating workers. However,
manual sandblasting is preferred by factories as it is cheaper because
it does not require investment in advanced and expensive industrial
equipment. Sand blasting also costs less than other fading methods (like
hand sanding) which are more labour intensive. Whilst sandblasting to
achieve a worn look on denim is a relatively new phenomenon in the
clothing industry, similar methods have been widely used in mining and
building industries for many decades and the link between the use of
sand blasting and the risk of silicosis has long been acknowledged.

It
was the high health risks associated with manual sand blasting process
that prompted regulation of the technique in the Europe in the 1960s.
Sand blasting can expose workers to extreme health hazards and can cause
death within months or years of starting work as a sandblaster. Sand
blasting using natural sand is especially problematic because workers
inhale crystalline silica dust particles during production, causing
serious damage to the respiratory passages. These particles are so tiny
that they are invisible to the naked eye.

The body is unable to
expel the silica particles, causing diseases such as silicosis. The
particles penetrate the pulmonary alveoli and the connective tissue,
gradually impairing lung capacity and the workers’ ability to oxygenate
blood. Symptoms include shortness of breath; as the disease develops,
this is common even when resting. This puts additional strain on the
heart, eventually leading to death. However, the progress of silicosis
can be slowed if symptoms are diagnosed at an early stage.You may also like: